The present invention concerns a shed forming arrangement for looms.
One form of shed forming arrangement for a loom comprises lift elements which are movable in opposite relationship to each other and hooks which are associated with the lift elements. The hooks are connected in pairs by connecting members forming loops which pass around rollers which act on the shedding means such as the heald train or harness train of the loom. Arresting elements are movable between an engagement position with the respective hook and a non-engagement position, the positions of the arresting elements being influenced by respective actuating devices which each have a piezoelectric flexural or bending transducer stationarily clamped at one end. A shed forming arrangement for a loom of that kind is known from WO 93/01337, with the piezoelectric flexural transducers disposed in such a way that they displace the arresting element, for example move thrust elements. However piezoelectric transducers are inherently not suitable for producing levels of mechanical output of useful orders of magnitude. Problems with the arrangement outlined above occur in particular for example when the arresting elements are to be moved for the first time after being stationary for a prolonged period and also if the ease of movement of the arresting elements is reduced due to soiling which has occurred, as in such situations the respective piezoelectric flexural transducer is required to produce more force than under normal operating conditions. However the transducer is unable to produce that force.